Scallop Sizes Explained, From U10 to 30/40

Scallop sizes look like code the first time you see them on a label: U10, 10/20, 20/30. Once you know the trick, though, the size is the most useful number on the package, because it tells you exactly what you are buying and how it will cook.

This guide explains scallop sizes from the biggest U10s down to little bay scallops, what the U actually stands for, how much each grade weighs, and which size to reach for when you want a deep golden sear. Get the size right and everything from your timing to your plating gets easier.

TL;DR

• Scallops are sized by how many it takes to make a pound, so a lower number means bigger scallops.
• The U in U10 stands for “under,” so U10 means under 10 scallops per pound, the largest grade.
• Sea scallops run roughly U10 to 30/40; bay scallops are tiny, 70 to 100 per pound.
• For a golden sear, buy big and dry (U10 or 10/20); small grades cook through before they brown.
• Plan on about 1/3 to 1/2 pound of scallops per person for a main course.

How are scallops sized?

Scallop sizing looks like code until you know the trick: the numbers are a count per pound. A size tells you roughly how many scallops it takes to make one pound, so a lower number means bigger scallops and a higher number means smaller ones. A pound of 10/20 scallops holds 10 to 20 pieces, while a pound of 20/30 holds 20 to 30, so each one is smaller. The count is the fastest way to know what you are actually buying, and it is far more useful than words like jumbo that no one regulates.

An example makes it click. If a recipe calls for 12 large scallops and you buy U10s, that is a little over a pound of seafood. Buy 20/30s instead and the same dozen weighs about half as much, cooks faster, and can look lost on the plate. Matching the size to the recipe keeps your timing and your portions honest.

What does the U in U10 mean?

The letter U stands for under. U10 means under 10 scallops per pound, so each one weighs more than about 1.6 ounces, and U12 means under 12 per pound. The U grades are the largest scallops on the market. You will also see super colossal or colossal on labels, but those words are marketing, not a standard. The count is the number that matters, so when a size is written U10, read it as the big ones, fewer than ten to a pound.

What are the common scallop size grades?

Here is how the usual sea scallop grades line up, largest to smallest. As a rule, the bigger the scallop, the easier it is to sear without overcooking the center, and usually the higher the price per pound.

• U10: under 10 per pound, the largest, best for a showpiece sear.
• 10/20: 10 to 20 per pound, big and easy to cook, a common restaurant size.
• 20/30: 20 to 30 per pound, medium, good all-purpose scallops.
• 30/40: 30 to 40 per pound, smaller, fine for pasta and stir-fries.

What does each grade weigh, and how many do you need?

Turn the count into ounces and the grades stop being abstract. Divide 16 ounces by the count and you get the weight of one scallop: a U10 runs more than 1.6 oz apiece, a 10/20 averages about 1.1 oz, a 20/30 lands near 0.65 oz, and a 30/40 is about 0.45 oz. That is a scallop three times the size of another one, sold under the same word on a menu.

Portioning follows from there. Plan on 1/3 to 1/2 pound of scallops per person for a main course, which works out to 4 or 5 U10s, 6 to 8 pieces of 10/20, or a dozen 20/30s. As an appetizer, 3 large scallops per person is plenty.

• U10: a showpiece, 4 or 5 per plate, the size you buy when the scallop is the dish.
• 10/20: the everyday main-course scallop, 6 to 8 per person.
• 20/30: skewers, pasta, tacos, and salads, where you want scallop in every bite.
• 30/40: chowders, stir-fries, and fried rice, dropped in whole.
• Bay scallops, 70 to 100 per pound: chowder, ceviche, and quick sautes only.

How can you spot a dry scallop before you buy?

You can usually tell dry from wet by looking, and it takes about five seconds. Dry scallops are ivory, cream, pale pink, or slightly tan, and the pieces vary a little in color from one to the next. Wet scallops are uniformly bright, opaque, and a slightly unnatural white, because a phosphate solution bleaches out that variation.

Then look under them. Dry scallops sit on the tray nearly dry and feel tacky, almost sticky, when you touch one. Wet scallops sit in a milky pool that keeps refilling, because they are steadily leaking back the water they absorbed. The label settles it: dry scallops are sold as dry, dry-packed, chemical free, or all natural, and the ingredient list says scallops and nothing else. If you see sodium tripolyphosphate, STP, or the phrase treated to retain moisture, you are looking at wet scallops. When there is no label at all, ask, and a good counter will tell you straight.

What else is on a scallop label?

Past the count and the dry-or-wet question, a label carries a few details that change what you get. Species is the first: the sea scallop is Placopecten magellanicus out of the Northwest Atlantic, bay scallops are a smaller separate animal, and Hokkaido scallops are large sweet scallops from cold Japanese waters.

Next, look for how they were frozen. IQF means individually quick frozen, so the pieces stay loose and you can thaw four instead of twenty, while block frozen means the whole lot thaws together, fine for a party and a nuisance on a Tuesday. A net weight, or a note that the weight was taken after glazing, tells you the ice was not counted as scallop. Two other phrases carry real information: day boat means the catch landed the same day it was pulled, while most sea scallops come off trips that run a week or more, and previously frozen on a fresh counter tells you these were thawed for you, so plan to cook them rather than refreeze them at home.

Should you think in price per scallop, not per pound?

The sticker shock on big scallops eases once you do the division. Take the price per pound, divide it by the middle of the count range, and you have the cost of one scallop on the plate. A pound of U10s is 8 or 9 pieces; a pound of 20/30s is closer to 25. If you are plating 4 large scallops per person, U10s at a higher price per pound may cost only a little more per serving than a smaller grade you would have to pile up. If the scallops are going into a chowder where nobody sees them whole, that higher grade is money spent on a size that gets diced away.

One warning on bargains: wet scallops usually show the lowest price per pound and are the worst value on the shelf. You pay scallop prices for absorbed water, much of which leaves in the pan, so the piece on your fork is smaller than the one you bought.

What should you ask at the fish counter?

Fishmongers know the answers and are rarely asked. Five questions get you everything you need, and it helps to ask for even sizing while you are there, since a tray mixing 1.6 oz and 0.9 oz scallops cooks unevenly no matter what you do.

• Are these dry or wet? If the answer is vague, ask to see the box or the tag.
• What is the count per pound? Not the adjective, the number.
• Sea or bay scallops? The price gap between them is large.
• Were these previously frozen, and what day did they come in?
• Has the side muscle been removed, or should I plan to pull it myself?

What is the difference between sea and bay scallops?

Size grading mostly describes sea scallops, the large ones. The Atlantic sea scallop is the species behind most of what you sear, and the part you eat is its adductor muscle, the round column that works the shell. Bay scallops are a different, much smaller animal, often 70 to 100 per pound. They are sweet and tender but tiny, better suited to quick sautes, chowders, and pasta than to a hard sear. If a recipe wants seared scallops with a crust, it means sea scallops.

Which size scallop is best for searing?

For a restaurant-style sear, go big. U10 or 10/20 scallops have enough mass to build a deep golden crust before the center overcooks, which is the whole challenge with scallops, and smaller grades cook through before they brown. Cost tracks size, so there is a trade-off: U10 scallops carry the highest price per pound, because fewer, larger meats are harder to land and grade. If you are cooking for a crowd or building a stew, 20/30s give you sweet scallop flavor for less, so save the U10s for the nights the sear is the star.

Size is only half of it, though. Dry versus wet decides whether a scallop sears at all. Dry scallops have no additives, while wet scallops are treated with a phosphate solution that makes them soak up water, so they weigh more and steam in the pan. Even a U10 wet scallop will not brown well. Buy dry-packed scallops in a large size and you have both halves of a good sear.

Ready to sear the best scallops you can buy?

Now that you can read scallop sizes at a glance and know why big and dry is the combination to look for, the shopping is easy. For the biggest, sweetest scallops for searing, reach for Maine Shelled Lobster's super-colossal Hokkaido scallops, large cold-water scallops sized for exactly this, shipped flash-frozen across the continental U.S. Pick your size, keep them dry, and give them a hot, dry pan.

Frequently asked questions

What does U10 mean for scallops?

U10 means under 10 per pound, so each scallop weighs more than about 1.6 ounces. These are the largest scallops and the best for searing.

What is the difference between 10/20 and 20/30 scallops?

The numbers are counts per pound. 10/20 scallops run 10 to 20 per pound and are larger; 20/30 run 20 to 30 per pound and are smaller. Lower numbers mean bigger scallops.

Are bigger scallops better?

For searing, yes, because they build a crust before overcooking. For chowders, pasta, or quick sautes, smaller sea scallops or bay scallops are fine and cost less.

What is the difference between sea and bay scallops?

Sea scallops are large, often 10 to 30 per pound, and sear well. Bay scallops are tiny, roughly 70 to 100 per pound, sweet, and best for quick cooking, not a hard sear.

What size scallops should I buy to sear?

U10 or 10/20 dry-packed sea scallops. Big and dry is the combination that gives you a golden crust.

How many scallops do I need per person?

About 1/3 to 1/2 pound for a main course. That is 4 or 5 U10 scallops, 6 to 8 of the 10/20 grade, or roughly a dozen 20/30s. For an appetizer, 3 large scallops per person is enough.

How can I tell dry from wet scallops at the store?

Look at the color and the tray. Dry scallops are ivory to pale pink and sit almost dry; wet scallops are uniformly bright white and sit in a milky pool. The ingredient list on dry scallops says scallops and nothing else.